clarify the issue with where_object_changes for numeric values

History
---
[The first problem mention](1ad7838).
[The major issue](#803) with relevant discussions.

Details
---
I see the problem only with one specific case – when the method is `where_object_changes` and the serializer is YAML. Which is a default configuration.

I see there are 6 types of queries with a numeric value for `where_object_changes` and `where_object` (grabbed from `version_spec.rb`):
```
SELECT "versions".* FROM "versions" WHERE "versions"."item_id" = 1 AND "versions"."item_type" = 'Widget' AND (object_changes @> '{"an_integer":[1]}')  ORDER BY "versions"."created_at" ASC, "versions"."id" ASC

SELECT "versions".* FROM "versions" WHERE "versions"."item_id" = 1 AND "versions"."item_type" = 'Widget' AND ("versions"."object_changes" ILIKE '%
an_integer:
- 1
%' OR "versions"."object_changes" ILIKE '%
an_integer:
-%
- 1
%')  ORDER BY "versions"."created_at" ASC, "versions"."id" ASC

SELECT "versions".* FROM "versions" WHERE "versions"."item_id" = 1 AND "versions"."item_type" = 'Widget' AND (((object_changes->>'an_integer' ILIKE '[1,%') OR (object_changes->>'an_integer' ILIKE '[%,1]%')))  ORDER BY "versions"."created_at" ASC, "versions"."id" ASC

SELECT "versions".* FROM "versions" WHERE (object @> '{"an_integer":1}')

SELECT "versions".* FROM "versions" WHERE (object->>'an_integer' = '1')

SELECT "versions".* FROM "versions" WHERE ("versions"."object" ILIKE '%
an_integer: 1
%')
```

The only problematic one is `#2`. It incorrectly matches `object_changes` like
```
---
name:
-
- Kimberli
an_integer:
-
- 0
created_at:
-
- 2017-09-28 18:30:13.369889000 Z
updated_at:
-
- 2017-09-28 18:30:13.369889000 Z
id:
-
- 1
---
name:
- foobar
- Hayes
an_integer:
- 77
- 1
updated_at:
- 2017-09-28 18:30:13.383966000 Z
- 2017-09-28 18:30:13.395539000 Z
```

README.md

@@ -246,9 +246,11 @@ version.index
 version.event
 
 # Query the `versions.object` column (or `object_changes` column), by
-# attributes, using the SQL LIKE operator. Known issue: inconsistent results for
-# numeric values due to limitations of SQL wildcard matchers against the
-# serialized objects.
+# attributes, using the SQL LIKE operator.
+#
+# Known issue: `where_object_changes` with the default YAML serializer and
+# an `object_changes` text column may return incorrect results for numeric values
+# due to limitations of SQL wildcard matchers against the serialized objects.
 PaperTrail::Version.where_object(attr1: val1, attr2: val2)
 PaperTrail::Version.where_object_changes(attr1: val1)
 ```

spec/models/version_spec.rb

@@ -107,6 +107,10 @@ module PaperTrail
 
       column_overrides.shuffle.each do |column_datatype_override|
         context "with a #{column_datatype_override || 'text'} column" do
+          let(:widget) { Widget.new }
+          let(:name) { FFaker::Name.first_name }
+          let(:int) { column_datatype_override ? 1 : rand(5) + 1 }
+
           before do
             if column_datatype_override
               # In rails < 5, we use truncation, ie. there is no transaction
@@ -147,10 +151,6 @@ module PaperTrail
           end
 
           describe "#where_object", versioning: true do
-            let(:widget) { Widget.new }
-            let(:name) { FFaker::Name.first_name }
-            let(:int) { rand(10) + 1 }
-
             before do
               widget.update_attributes!(name: name, an_integer: int)
               widget.update_attributes!(name: "foobar", an_integer: 100)
@@ -172,6 +172,9 @@ module PaperTrail
               end
 
               it "locates versions according to their `object` contents" do
+                expect(
+                  PaperTrail::Version.where_object(an_integer: int)
+                ).to eq([widget.versions[1]])
                 expect(
                   PaperTrail::Version.where_object(name: name)
                 ).to eq([widget.versions[1]])
@@ -191,6 +194,9 @@ module PaperTrail
               end
 
               it "locates versions according to their `object` contents" do
+                expect(
+                  PaperTrail::Version.where_object(an_integer: int)
+                ).to eq([widget.versions[1]])
                 expect(
                   PaperTrail::Version.where_object(name: name)
                 ).to eq([widget.versions[1]])
@@ -206,13 +212,9 @@ module PaperTrail
           end
 
           describe "#where_object_changes", versioning: true do
-            let(:widget) { Widget.new }
-            let(:name) { FFaker::Name.first_name }
-            let(:int) { rand(5) + 2 }
-
             before do
               widget.update_attributes!(name: name, an_integer: 0)
-              widget.update_attributes!(name: "foobar", an_integer: 77)
+              widget.update_attributes!(name: "foobar", an_integer: 100)
               widget.update_attributes!(name: FFaker::Name.last_name, an_integer: int)
             end
 
@@ -231,7 +233,7 @@ module PaperTrail
                   widget.versions.where_object_changes(name: name)
                 ).to eq(widget.versions[0..1])
                 expect(
-                  widget.versions.where_object_changes(an_integer: 77)
+                  widget.versions.where_object_changes(an_integer: 100)
                 ).to eq(widget.versions[1..2])
                 expect(
                   widget.versions.where_object_changes(an_integer: int)
@@ -240,7 +242,7 @@ module PaperTrail
 
               it "handles queries for multiple attributes" do
                 expect(
-                  widget.versions.where_object_changes(an_integer: 77, name: "foobar")
+                  widget.versions.where_object_changes(an_integer: 100, name: "foobar")
                 ).to eq(widget.versions[1..2])
               end
             end
@@ -257,7 +259,7 @@ module PaperTrail
                     widget.versions.where_object_changes(name: name)
                   ).to eq(widget.versions[0..1])
                   expect(
-                    widget.versions.where_object_changes(an_integer: 77)
+                    widget.versions.where_object_changes(an_integer: 100)
                   ).to eq(widget.versions[1..2])
                   expect(
                     widget.versions.where_object_changes(an_integer: int)
@@ -266,7 +268,7 @@ module PaperTrail
 
                 it "handles queries for multiple attributes" do
                   expect(
-                    widget.versions.where_object_changes(an_integer: 77, name: "foobar")
+                    widget.versions.where_object_changes(an_integer: 100, name: "foobar")
                   ).to eq(widget.versions[1..2])
                 end